System and method for improved auto-boating

ABSTRACT

According to one embodiment of the invention, a method for auto-boating includes supporting a tape substrate having first and second end portions on a boat, sandwiching the first and second end portions between respective ones of a pair of end sleeves and the boat, coupling a boat clip to the boat, and removing the end sleeves from between the first and second end portions and the boat clip.

This is a divisional of application Ser. No. 10/724,325 filed Nov. 21,2003.

TECHNICAL FIELD OF THE INVENTION

This invention relates generally to the field of integrated circuitpackaging and, more specifically, to a system and method for improvedauto-boating.

BACKGROUND OF THE INVENTION

Because of the sheer volume of integrated circuits in the marketplace,packaging of integrated circuits in a manner that is cost-effective withhigh yield is important for semiconductor manufacturers in order thatthey can be competitive in the marketplace. One important process in thefabrication of integrated circuits is the die attach process. Because ofthe ever decreasing thickness of some substrates, such as tapesubstrates, the die attach process becomes even more important becauseof the challenges present when attaching die to these types ofsubstrates.

The auto-boating process, which sandwiches a tape substrate between aboat and a clip, greatly enhances the die attach process for tapesubstrates. However, since the clip holds down only a very small stripof the substrate along its edges, the possibility of the substrate edgesgetting jammed with the clip windows at the ends of the clip is highbecause of the coiling effect when placing a tape substrate on a boat.This leads to substrate bowing and warping along its edges, which meansthat the integrated circuit dies formed along the edges of the tapesubstrate may have to be scrapped, which hurts yield.

SUMMARY OF THE INVENTION

According to one embodiment of the invention, a method for auto-boatingincludes supporting a tape substrate having first and second endportions on a boat, sandwiching the first and second end portionsbetween respective ones of a pair of end sleeves and the boat, couplinga boat clip to the boat, and removing the end sleeves from between thefirst and second end portions and the boat clip.

Some embodiments of the invention provide numerous technical advantages.Other embodiments may realize some, none, or all of these advantages.For example, a pair of end sleeves are utilized in an auto-boatingprocess to hold the ends of the tape substrate flat against the boatwhile the boat clip is pressed down over the tape substrate. Thissubstantially eliminates the possibility of contact between the edges ofthe tape substrate and the clip windows. Hence, any bowing/warping alongthe edges of the tape substrate is eliminated. This improvedauto-boating process is a simple drop-in step that avoids having tochange the length of the tape strip from which the tape substrate isformed.

Other technical advantages are readily apparent to one skilled in theart from the following figures, descriptions, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the invention, and for furtherfeatures and advantages, reference is now made to the followingdescription, taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is an exploded perspective view of a system used in auto-boatingaccording to one embodiment of the present invention;

FIG. 2 illustrates the bowing of a prior art tape substrate beingsandwiched between a boat and a boat clip; and

FIGS. 3A through 3D are elevation views of a simplified auto-boatingprocess according to one embodiment of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

Example embodiments of the present invention and their advantages arebest understood by referring now to FIGS. 1 through 3D of the drawings,in which like numerals refer to like parts.

FIG. 1 is an exploded, perspective view of a system 100 utilized in anauto-boating process according to one embodiment of the presentinvention. The auto-boating process is well known in the integratedcircuit fabrication industry. Hence, all details of such a process maynot be fully described herein. Generally, system 100 is utilized in thefabrication of integrated circuits, such as ball grid arrays (“BGAs”).In the illustrated embodiment, system 100 includes a boat 102, a boatclip 104, a pair of end sleeves 109, and a tape substrate 106 having aplurality of die attach regions 108 in which integrated circuit die arecoupled thereto in order to fabricate individual integrated circuits.

Generally, boat 102 is used as a carrier for tape substrate 106 duringthe fabrication of integrated circuits and boat clip 104 secures tapesubstrate 106 to boat 102. Boat clip 104 facilitates the die attachprocess for tape substrate 106 by including a plurality of windows 110formed therein that expose die attach regions 108 on tape substrate 106.Both boat 102 and boat clip 104 may formed from any suitable material;however, boat 102 and boat clip 104 are typically formed from a suitablemetal.

Because tape substrate 106 may be very thin in some embodiments, boat102 and boat clip 104 are needed to secure tape substrate 106 in placeso that integrated circuit die may be attached to tape substrate 106 inan accurate and cost-efficient manner. As a brief example of thefabrication process for integrated circuits utilizing system 100,integrated circuit die (not shown) are attached to respective die attachregions 108 on tape substrate 106, a suitable wire bonding processcouples the integrate circuit die to the appropriate contacts on eachdie attach region 108, and then tape substrate 106 is transferred to thenext assembly station so that a suitable encapsulation process may takeplace. After encapsulation, a suitable ball attach process is utilizedto attach solder balls to the underside of a tape substrate 106 beforethe integrated circuits are singulated with a suitable singulationprocess.

Since tape substrate 106 receives integrated circuit die, it isimportant for die attach regions 108 of tape substrate 106 to berelatively planar without any bowing and/or warping before theintegrated circuit die are attached thereto. Bowing and warping problemsof die attach regions 108 proximate each end of tape substrate 106 hasbeen discovered using prior auto boating systems. An example of suchsubstrate bowing is illustrated in FIG. 2.

Referring to FIG. 2, the bowing of prior art tape substrate 200 isillustrated. Tape substrate 200 is sandwiched between a boat 201 and aboat clip 202. Typically, the bowing problem occurs because a lateraledge 206 of tape substrate 200 contacts the edges of clip windows 204formed in boat clip 202 as boat clip 202 is positioned over substrate200 during the coupling of boat clip 202 to boat 201 that is supportingtape substrate 200. This is because after tape substrate 200 is placedon boat 201, tape substrate 200 is not totally flat and “coils” upwardalong its longitudinal edges to form a somewhat concave surface. As boatclip 202 is placed on top of tape substrate 200 in order to sandwichtape substrate 200 between boat 201 and boat clip 202, the possibilityof lateral edge 206 getting jammed with clip windows 204 is very high.With reference to FIG. 1, the present invention addresses this problem,in one embodiment, by providing end sleeves 109 to hold down endportions 111, 113 of tape substrate 106 one boat 102 before boat clip104 is placed over tape substrate 106 and coupled to boat 102. Thiscounteracts the coiling effect and eliminates the possibility of lateraledges 107 a, 107 b of tape substrate 106 getting jammed with clipwindows 110. The utilization of end sleeves 109 is described in moredetail below in conjunction with FIGS. 3A through 3D.

FIGS. 3A through 3D are longitudinal elevation views of a simplifiedauto-boating process according to one embodiment of the presentinvention. Referring to FIG. 3A, tape substrate 106 having end portions111 and 113 is supported by boat 102. The slight curvature of tapesubstrate 106 is meant to illustrate the coiling effect that takes placewhen tape substrate 106 is placed on boat 102. As described above, thiscoiling effect has led to bowing and/or warping problems of die attachregions 108 proximate end portions 111 and 113 of tape substrate 106 inprior auto-boating systems. To prevent this, the present inventionutilizes end sleeves 109 in a manner described below in conjunction withFIGS. 3B through 3D.

FIG. 3B illustrates end sleeves 109 sandwiching end portions 111 and 113of tape substrate 102 between end sleeves 109 and boat 102. In oneembodiment, end sleeves 109 are horizontally extended, as denoted byarrows 300, by automated machines to cover end portions 111 and 113. Anysuitable width 302 of each end portion 111, 113 may be sandwichedbetween a respective end sleeve 109 and boat 102; however, in oneembodiment, width 302 is between approximately two millimeters and sixmillimeters. In a more particular embodiment, width 302 is approximatelyfour millimeters. The larger the width 302 is, the greater risk ofdamage of die attach regions 108 proximate end portions 111 and 113.Because lateral edges 107 a, 107 b are typically square edges, endsleeves 109 are generally rectangularly shaped.

FIG. 3C illustrates boat clip 104 being coupled to boat 102 while endsleeves 109 are holding down end portions 111 and 113 of tape substrate106. Because boat clip 104 is coupled to boat 102 while end sleeves 109are performing their function, end sleeves 109 preferably are formedfrom a relatively thin material. For example, a thickness 304 of endsleeves 109 is no more than 0.675 millimeters. Although boat clip 104may be coupled to boat 102 in any suitable manner, typically boat clip104 is magnetically coupled to boat 102. The coupling force between boatclip 104 and boat 102 is such that it is great enough to secure tapesubstrate 106 therebetween for subsequent attaching of integratedcircuit die on die attach regions 108, yet small enough to be able toremove end sleeves 109 from therebetween.

FIG. 3D illustrates the retraction of end sleeves 109 from between boatclip 104 and boat 102, as denoted by arrows 306. Because width 302 isrelatively small, end sleeves may be easily removed from between boatclip 104 and boat 102 without damaging end portions 111 and 113 of tapesubstrate 106. Any suitable automated machine may function to retract orremove end sleeves 109 therefrom.

Thus, utilization of end sleeves 109 to hold down end portions 111 and113 of tape substrate 106 as boat clip 104 is coupled to boat 102eliminates the possibility of contact between lateral edges 107 a and107 b of tape substrate 106 and clip windows of boat clip 104 to preventsubstrate bowing and/or warping. Integrated circuit die may then beattached to die attach regions 108 without having to worry about anybowing and/or warping that may affect the quality and reliability of thecompleted integrated circuits.

Although embodiments of the invention and their advantages are describedin detail, a person skilled in the art could make various alterations,additions, and omissions without departing from the spirit and scope ofthe present invention, as defined by the appended claims.

1. A system used in auto-boating, comprising: a boat; a tape substratehaving first and second end portions configured to support the boat; apair of end sleeves operable to sandwich respective ones of the firstand second end portions between the end sleeves and the boat; and a boatclip configured to couple to the boat.
 2. The system of claim 1, whereinthe end sleeves are operable to horizontally extend toward and away fromthe tape substrate.
 3. The system of claim 1, wherein the end sleevesare rectangularly shaped.
 4. The system of claim 1, wherein the endsleeves have a thickness of no more than 0.675 millimeters.
 5. Thesystem of claim 1, wherein the end portions have a width of betweenapproximately two millimeters and six millimeters.
 6. The system ofclaim 1, wherein the end portions have a width of approximately fourmillimeters.
 7. The system of claim 1, wherein the tape substrate isformed from polyimide.
 8. The system of claim 1, wherein the boat clipis operable to magnetically couple to the boat.